Time limit contactor



Nov. 6, 1934. w scHAl-:LCHLIN er AL 1,979,709

TIME LIMIT CONTACTOR Filed May 11, 1933 2 Sheets-Sheet l ATrRNEY Nov. 6, 1934. wl scHAELcHLIN Er A1. 1,979,799

TIME LIMIT CONTACTOR Filed May 11, 193:5 2 sheets-sham 2 WITNESSES: INVENTORS.

09M f. BY

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Patented Nov. 6, 1934 PATENT OFFICE TIME LIMT CDNTACTOB Walter Schaelchlln, Wilkinsburg,

Frisch, Pittsburgh, Pa., house Electric & M

and Erling assignors to Westinganufacturing Company,

East Pittsburgh, Pa., a corporation of Pennsylvania Application May 11, 1933, Serial No. 670,498

16 Claims.

Our invention relates generally to electromagnetic devices and more particularly, to time limit contactors.

In the design and construction of electromagnetic devices, or contactors, it is often desirable to provide for a long and definite `delay in the operation of a device. Heretofore the interval of time obtained by the use of such devices has been too short in many instances and, as a result, additional and auxiliary devices had to be used to provide the necessary time delay.

One object of our invention is the provision of a time limit contacter, or Timetactor, that shall be simple in structure and design, eflicient in operation, and which may be readily and economically manufactured.

A further object of our invention is to provide for an adjustable relatively large time constant in the operation of electromagnetic devices.

Other broad, as well as more specific, objects of our invention will become more apparent from a study of the following specification when considered in conjunction with the accompanying drawings, in which:

Figure 1 is a view in side elevation, partly in section, of a time-limit electromagnetic contactor constructed in accordance with our invention; l

Fig. 2 is a front elevational view of the contactor illustrated in Fig. 1; v

Fig. 3 is a perspective view of the arrangement of the contact members on the electromagnetic time-limit device;

Fig. 4 is a diagram showing one accelerating contacter or Timetactor, embodying the fea- Y tures of our invention, associated with a starting control system;

Fig. 5 shows a number of curves which demonstrate the characteristics possessed by the electromagnetic time-limit device constructed in accordance with our invention as compared with other types of electromagnetic time limit devices; and

Fig. 6 shows diagrammatically a modified arrangement of the coils oi our time limit device.

Referring now to the drawings, the electromagnetic time limit device, or Timetactor, illustrated, comprises a frame 30, in which a core 31 is mounted. The core member 31 may be mounted in any suitable manner and in this particular showing, a bolt 32 cooperating with the frame 30 and having threaded engagement with the core, is utilized. Extending substantially parallel to the core member 31 is a support 33 which,

in this instance, is constructed to be substantially integral with the base of the frame 30.

An armature 34 is mounted on the support 33 and is disposed in alignment with the core 31; To mount the armature for oscillatory movement, a 50 notch 36 may be provided at the end of the supporting member 33. In the construction illustrated, the notch 36 is provided at the -junction of the end portion of support 33 and a plate 35 mounted on top oi the support and extending a short distance beyond the end of the support.

The simplest type of armature that is suitable for this electromagnetic time limit device is aI metal plate which is cut square at the end, or preferably out by planes forming an acute angle 7 at one edge of the end of the armature adjacent the end of the support 33. Further, to provide for a free pivotal movement of the armature when mounted in the notch 36, the walls dening 'the notch should be spaced at an angle greater than a right angle. The size of the angle of the notch as well as the size oi the acute angle at the upper end of the armature will be determined by the desired angle of swing of the armature. In this embodiment of our invention, to make the notch of the desirable angular extent, the plate 35 is bent upwardly at a point near the upper righthand end of the support 33. ,A It will be readily understood that a suflicient and free angular motion of the armature may be obtained if the angle of the notch 36 is made slightly greater than the sum 0i the angle of movement and the acute angle at the knife edge of the armature coacting with the notch 36.

In order that the armature may be readily mounted, removed, and replaced, a rectangular notch 33 is cut in the projecting bent portion of the plate 35. In cutting the notch, the plate 35 is cut at two places to form a tongue 39 which ls bent upwardly much more than the end portion of plate 35 forming, in part, the notch 36. As shown, a bracket 40 is mounted on the armature and provided with an extension or tongue 41 which extends through the notch 38.

The upper tongue 39, which is integral with 10o plate 35, is provided with a slot 42, extending inwardly from the end, for receiving a bolt 43, while the tongue 41 has an opening through which the bolt extends. A spring 45 is mounted on the bolt 43 and is disposed to bias the armature 34 counterclockwise about the knife edge 37. In this manner, the armature is retained in position, the tongue 41 engages the two sides of the notch 38 to prevent lateral movement, while the Spring is biases it upwardly inte the notch as. 11

. The armature may be readily removed by ccmpressing the spring and forcing the bolt 43 upwardly and out of slot 42. l y

As shown, the bolt 43 is provided withv an adjustable nut 46 whereby any desired spring ten- I armature rmly against the amature receiving l5 v surface 60. Y v

The armature is also provided with auxiliary contact members 14. As will be apparent from Figs. 3 and 4, contact members 26 and 27 engage before contact members 14 -are opened. This feature is desirable when utilizing ourV contactorhowever,- not very important'in this invention.

The important feature is that the armature, actuated by the adjustable spring 45 and controlled y by the tube or sleeve 23 and the effect of the coils 5 and 11, moves to close contact 'members 26 and 27 a longer time interval after the attendant has set up the necessarycircuits for the operation of the contactor than any electromagneic time limit relay or electromagnetic contactor heretofore known to us. A

The core 31 is provided-with an armature receiving face 60. A copper'sleeve 23 is mounted directly on the core. This sleeve need not necessarily be of copper but may be silver, aluminum, or any other material having a relatively low re@ sistance value, and of such properties that currents are induced therein when the magnetic ux threading thel sleeve, i. e., the iiux in the core 31, is varied. To actuate the armature 34, a main magnetizing coil 1l is mounted o'n the sleeve 23. As will be readily understood, this coil 11 may be constructed to have any desired number of turns of suitable conductors, which will depend on operating conditions to be met.

As shown, a neutralizing coil 5 is mounted on themagnetizing coil. 'I'his coil is so constructed,

.arranged and energized as to oppose the magnetic tion, and the numberof turns provided in the coil 5, will depend upon the main actuating coil 11 .and the manner in which it is desired to dissipate the residual magnetism or preferably the lrate at which it is desired to dissipate the residual magnetism that may, in the absence of the neutralizing coil, be retained by the core 31 during the operation of the contactor.

In Fig. 6,'the sleeve 23, coil 11 and coil 5,

are replaced by a ring 23', mounted directly on the core 31 at one end thereof; a coil 11', serving ,as a main magnetizing coil, mounted at the mid features of our invention can probably be had from a discussion of the operation of the time- Lavare@ sistor 4 and conductor 7 to the bus 8. The neutralizing coil 5.of the timev limit contactor, or 'Iimetactor" 6 is shown interconnected with resistor 4 by a potentiometer circuit arrangement whereby the eiect of theneutralizing coil may be varied at will.

If the starting switch 10 is operated, a circuit is established from the bus 1 through .conductor 9, starting switch 10, th main or magnetizing coil 1l of the contactor 6 and back contact members 12 b( the line, or armature contactor 16, to the bus 8l Operation of the contactor 6 effects'the insertion of the resistor 21 in the .armature circuit of the motor 20 at the opening of the contact members 26 and 27, and also eiect the closing of contact members 14.

A The closing of contact members 14 eects the energization of the actuating coil 15 of the armature contactor 16 through stop switch 13and the contact members .14. The contactor 16 is thus actuated, closing contact members 22 for the motor and contact members 18 for a selfholding circuit through conductor 17 and contact vmembers 18.

n win be noted that the operation of the contactor 16 causes the opening of the contact mem- -bers 12 an instant after the closing of the contact members 22. The energizing circuit for the main or magnetizing coil 11 of the contactor 6 is thus interrupted, and the motor circuit is established from bus 1 through the series'field 19, motor 20, starting resistor 21, conductor `28, and contact members 22 to the bus 8. The motor thus starts to accelerate. l

Interruption of the circuit forcoil 11 at contact members 12 induces a heavy current in the copper sleeve 23 in a direction tending to mainmotor circuit for -a denite time, which time is entirely independent of the load on the motor. After the current in the low resistance sleeve 23 tively weak, becomes important. Since the neutralizing coil 5 is designed andconnected to oppose the magnetizing coil 11, the residual magnetism is substantially annihilated, i. e. the decay 'v' or dissipation of the residual magnetism may be definitely controlled, and in consequence spring 45 rotates the armature 34 in a counter-clockwise direction on knife edge 37. Since spring 45 is adjustable the time constant is also a function of the spring adjustment.

Movement of the armature 34 removes the resistor 21 from the motor circuit by the'shunt circuit through conductors 24 and 25, and the contact members 26 and 27. l

In Fig. 5, the curve designated fNo shim",

shows the decay of the magnetic flux in the mag- .netic .circuit of a solenoid when the coil of the solenoid is deenergized. More particularly this curve shows the decay of the magnetic ux in`- the magnetic circuit of a relay such as is shown in Fig. 1 but wherein but one coil is used and no shim vis used between the armature 34 and core core 31.

Lannoo The curve designated "Shim" shows the decay of the magnetic ux in the magnetic circuit o! 'I'he curve designated Both coils" shows the' decay of the magnetic ilux in the magnetic circuit of a relay such as is shown in Fig. l when a main magnetizing coil and a neutralizing coil is used but wherein neither a shim nor a copper (silver or other metal) tube is used.

The subject matter appearing in the three paragraphs Just preceding explain the relation of the devices of the prior art with reference to the inventionherein disclosed, namely the use of a main magnetizing coil, a neutralizing coil, and a very low-resistance closed circuit or metal tube on the core. 'I'he curve designated Both coils and metal tube thus designates how the magnetic decay takes place and why along time constant is secured.

The use of a metal tube, a main magnetizing coil, a neutralizing coil, and a shim so far as known to us is not known in the prior art, but such arrangement except where the shim between armature 34 and core 31 is quite thin, would not be a desirable arrangement since the time constant would be decreased.

Fig. 5 shows more clearly how our new time contacter functions. With the best known electromagnetic time limit relays heretofore known to us, a maximum time constant of only a trifle over six seconds could be secured whereas with oui` device a maximum time constant of over twelve seconds can be secured. With a relay structure having two coils, namely, a magnetizing and a neutralizing coil, fairly reliable operation can be secured at about three seconds, whereas with our device, utilizing the combination of an adjustable neutralizing coil, a magnetizing coil and a copper tube, a very reliable operation can be obtained at six seconds.

Merely to further illustrate the novel and useful features ofv our invention, the following explanation of a practical application is given. lf it is assumed that a reliable operation for a set-up relay may be obtained at three seconds and a motor is to be normally accelerated to full speed in eighteen to twenty seconds, which usually involves the application of full voltage in fifteen seconds, then tive accelerating contactors and iive time limit set-up relays are needed.

However, ii' it is further assumed that a reliable operation for our time limit accelerating contactor may be obtained at not merely three, but five seconds, only three Timetactors are needed for the same operating conditions and the same motor. Consequently, in most cases the control system for any motor, assuming the starting characteristics that are usually required, will cost considerably less,in fact sometimes as low as onethird the cost of a control system for the same installation utilizing the ordinary set-up.

From the foregoing discussion, it is readily apparent that the combination of a closed circuit low-resistance coil, a magnetizing coil, a neutralfrom the scope thereof, it is intended that all matter contained in the above description or in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. In an electromagnetic time-limit device, in combination, a core member', an armature, means including an adjustable spring for biasing the armature away from said core, a main coil for magnetizing vthe core member to eiiect an operation'o! the armature, a control coil disposed to be energized 'when the main coil is deenergized to delay the decay of the magnetic flux produced by the main coil, and a third coil adapted to dissipate the residual magnetic ilux in the core members when the main coil is deenergized and in coaction with said control coil to increase the time during which the magnetism of the core dissipates at a rapid rate and thus increase the definite period oi time during which positive functioning or the armature may be obtained.

2. In an electromagnetic time-limit device, in combination, a core member, an armature disposed to coact with said core member, means for biasing said armature away from said core member, a coil for causing a magnetic ilux in said core member, a second coil for dissipating the tlux of said ilrst named coil when the nrst named coil is deenergized, and a low resistance closed circuit inductively related to said coil adapted to delay the dissipation of the magnetic flux when ysaid rst named coil is deenergized.

3. In an electromagnetic time-limit device, in combination, a magnetic circuit, means biased to one operating position and responsive to changes in magnetic iiux in the magnetic circuit to thereupon take a second operating position, a coil for producing a magnetic ilux in said magnetic circuit to cause said means to take said second operating position, a neutralizing coil adapted to lengthen the time during which the magnetism in the core member dissipates at a rapid rate when said first named coil is deenergized, and means for decreasing the rate of dissipation of the magnetic iux in the core member when said rst named coil is deenergized.

4. In an electromagnetic time-limit device, in combination, a magnetic circuit, means for producing a magnetic flux in said circuit, means for decreasing the rate of decay of said magnetic ux when said means for producing the iiux are rendered ineiective, and means for lengthening the time during which the ux decays in said magnetic circuit.

5. In an electromagnetic time-limit device, in combination, a magnetic circuit, a coil disposed to produce a magnetic ux in said circuit, a closed circuit inductively related to said coil for decreasing the rate of decay of the magnetic ux in said circuit when the coil is deenergized, and a neutralizing coil disposed to dissipate the residual magnetic flux in said circuit to continue the decay of the flux, whereby the time during which the decay is continued is lengthened.

6. In an electromagnetic time-limit device, in combination, a movably mounted armature, means for biasing the armature to predetermined positions, an electromagnet from which, when deenergized, the lines of magnetic force dissipate rapidly until substantially only the lines of magnetic force constituting the residual magnetism remain, means for decreasing the rate of dissipation of the magnetic force whereby a longer time is required for any given magnetic force to dissipate till only the residual magnetic force remains, and means, associated with the electromagnet. adapted to dissipate the residual magnetic torce when the electromagnet is deenergized to-continue said dissipation of the magnetic torce in the electromagnet to permit the operation ofthe armature under the iniluence of the biasing means.

"7. In an electromagnetic'time-limit device, in combination, a movably mounted armature, means for biasing-the armature to a predetermined position, anielectromagnet from which, when deenergized, the magnetic iiux decays at a rapid rate until substantially only the residual magnetic iiux remains, said electromagnet, when energized, being adapted to actuate said armature against said biasing means, control means for dissipating the residual magnetic ux of the electromagnet to increase the time during which the iuxdecays at 'a rapid rate, and means for decreasing the rate of the rapid decay to further lengthen the time during which the magnetic ilux dm, thereby increasing the time during whichthe positive functioning of the armature may be obtained in response to the force of said A 8. In an electromagnetic time-limit device, in combination, a movably mounted armature. adjustable means for adjustably biasing the armature to a predetermined position, an electromagnet from which, when deenergized, the magnetic ux decays at'a rapid rate until substantially only the residual magnetic iiux remains, said electromagnet, when energized, being adapted to actuate said armature against said biasing means-adjustable control means for dissipating the residual magnetic flux of the electromagnet to selectively increase the time by a substantially predetermined: amount during which the flux decays at a rapid rate, and means for decreasing the rate of the rapid decay to further lengthen the time during which the magnetic ux decays, thereby increasing the time during which the positive functioning of the armature'may be obtained in response to the force of said biasing means. Y

9. In an electromagnetic time-limit device, in combination, a frame, a core member carried by the frame and provided with an armature-receiving face, an armature supporting member mounted onthe frame, an armature disposed to cooperate with the core member and carried by the supporting member, said supporting member being provided with a notch for receiving an end of the armature, the end of the armature disposed in the notch being provided with a knife edge, the angular extent of the end of the armature about the knife edge being less than the angular spacing of the walls oi the notch, thereby to permit oscillatory movement of the armature in the notch, means for biasing the armature being disposed to retain the armature in position in the notch, a main energizing coil mounted on the core for drawing the armature into engagement with the core member, means Yfor decreasing the rate of decay of the magnetic ux produced'by said maincoil when said main coil is deenergized to thus increase the time of decay of the flux, and an auxiliary coil for dissipating the residual magnetic ux in the core when the main coil is deenergized, to permit said biasing means to actuate the armature out of engagement with the core.

10. In an electromagnetic time-limit device, in combination, a frame, a core member carried by the frame provided with an .armature receiving to a predetermined position, said biasing means face, an amature supporting member mounted on the frame, an armature disposed to cooperate with the core member and carried by the supporting member, said supporting member being provided with a notch for receiving an end of the armature, the end of the armature disposed in the notch being provided with a knife edge, the angular extent of the end of the armature about the knife edge being lessthan the angular spacing of the walls of the notch, thereby to permit oscillatory movement of the armature in the notch, adjustablel means for adjustably biasing the armature to a predetermined position, said biasing means 'being disposed to retain the armature in position in the notch, a main energizing coil mounted on the core for drawing the armature into engagement with the core member, for decreasing the rate of decay of the magnetic ux produced by said main coil when said main coil is deenergized to thus increase the time. of decay of the flux, and an auxiliary coil having means' for adjusting its eiect and thus adapted to dissipate at an adjustable rate the residual magnetic flux in the core when the main coil is deenergized, to thus permit said biasing means to actuate the armature out of engagement with the core.

11. In an electromagnetic time-limit device, in combination, a movably mounted armature, adjustable biasing means for biasing the armature to a. predetermined position, an electromagnet for actuating the armature against the action of said biasing means, means for causing the lines of flux to dissipate at a rapid rate and continuously to substantially zero upon the deenergizetion of the electromagnet, and means for decreasing the rate of dissipation of said iiux, whereby a positive operation of the armature is secured at a predetermined time after deenergization of said Aelectromagnet depending on the adjustment of said biasing means.

12. In an electromagnetic time-limit device, in combination, -a movably mounted armature, adjustable spring means for biasing the amature by any selected biasing force to a predetermined 12o position, an electromagnet disposed to actuate said armature against the action of said spring means, control means for decreasing the rate of decay of the magnetic ux of said electromagnet, and a coil associated with the electro e; et for dissipating the iiux, continuously, at substantially the rate determined by said rate control means,V and to substantially zero, upon the deenergizetion of the electromagnet, thereby to permit the positive operation of the armature at a predetermined instant depending upon the adjustmen of the-biasing means. Y Y

13. In an electromagnetic time-limit device, in combination, a core member, a spring biased armature cooperating with the core member, a coil for magnetizing the core member to effect the operation of the armature, means for controlling the rate of decay of the magnetic ux produced by said coil when the coil is deenergized, and an auxiliary coil adapted to eect a substantially constant rate of dissipation of the residual magnetism of the core from the maximum residual energized condition to zero, thereby to obtain operation of the armature at any predetermined time during the process of the dissipation of the l45 residual magnetism in response to the biasing force of the spring biased armature.

14. In an electromagnetic time-limit device, in combination, a core member, a spring biased armature in alignment with the core member,

means cooperating with the core member for varying the biasing force applied to the armature, a main coil for magnetizing the core member to effect the operation oi.' the amature, means for decreasing the rate of decay of the magnetic flux produced by said coil when the coil is deenergized, and an auxiliary coil, the magnetic effect of which may be varied, disposed to effect a substantially constant dissipation of the residual magnetism of the core from the maximum residual energized condition to zero, thereby to obtain a positive action of the armature at any predetermined time during the process of the dissipation of the residual magnetism in response to adjustments of said means for varying the biasing force of the spring biased armature.

15. In an electromagnetic time-limit device, in combination, a core member, an armature, a spring for biasing the armature to a predetermined position, a coil for magnetizing the core member to effect the operation of the armature, control means for decreasing the rate of dissipation of the magnetic flux in the core member when the coil is deenergized, and a neutralizing coil disposed to effect a substantially constant dissipation, at a rate determined by the control means, of the residual magnetism of the core from a maximum energized condition to zero, thereby to obtain a positive action of the armature at any predetermined time during the process oi dissipation of the residual magnetism.

16. In an electromagnetic time-limit device, in combination, a core member, an armature, a spring for biasing the armature to a predetermined position, spring means 'ior varying the biasing force of the spring, a main coil for magnetizing the core member to effect the operation of the armature, control means for decreasing the rate of dissipation of the magnetic flux in the core member when the main coil is deenergized, and a neutralizing coil disposed to eiect a substantially constant dissipation, at a rate determined by the control means, of the residual magnetism of the core from a maximum energized condition to zero, thereby to provide operation of the armature at any predetermined time during the process of dissipation of the residual magnetism, in response to adjustments of the means for varying the biasing force of the spring t'nat is applied to the armature.

WALTER SCHAELCHLIN. ERLING FRISCH. 

